Myeloperoxide, extracted from human neutrophils, will be assayed for anticryptococcal activity with the following types of Cryptococcus neoformans: encapsulated and nonencapsulated cells; human and soil isolated strains: yound and old cells after removal from long term maintence in vivo; cells cultured in soil for varying periods of time. Antifungal activity of human saliva will be assayed from individuals receiving various types of therapy. Attempts will be made to induce cryptococcosis in animals harboring long term infections of C. neoformans.